Currently, anti-cancer drugs are actively researched and developed. Effective techniques for research and development of the anti-cancer drugs may include (1) identification of an oncogene, (2) establishment of an oncogene-expressing cell, and (3) screening for an oncogene targeting drug.
(1) Identification of Oncogene
Anti-tumor effects of molecular targeting drugs that targets a particular oncogene (e.g., gefitinib) have attract attention, and the molecular targeting drugs having the anti-tumor effect have been developed. A method for identifying an oncogene that is promising as a novel molecule to be targeted is utilized in the development of such molecular targeting drugs. An example of such a method for identifying the oncogene is a method in which a gene library anticipated to include an oncogene is introduced into a cell and a gene introduced into the cell, which exhibits a transformation capacity, is selected as the oncogene (hereinafter a conventional identification method 1). For example, Non-patent Literature 1 discloses that a novel oncogene EML4-ALK was found by a transformation experiment utilizing a murine 3T3 cell (non-cancer cell).
Another example of the method for identifying the oncogene is a method in which gene expression is entirely analyzed between cancer cell or cancer tissue samples and normal cell or normal tissue samples using DNA chips or two dimensional electrophoresis and the oncogene is selected from the genes, expressions of which are different between the samples (hereinafter, conventional identification method 2).
(2) Establishment of Oncogene-Expressing Cell
A method for establishing an oncogene-expressing cell may include a method of isolating a cell line naturally expressing an oncogene from a subject as well as a method of introducing an oncogene together with a drug resistant gene (e.g., G418 resistant gene) into a cell and then selecting the cell carrying the oncogene using the drug (e.g., G418).
Patent Document 1 discloses that a cell line capable of proliferating in the presence of a ligand or a ligand-like substance and a drug corresponding to a drug resistant gene can be established by introducing a ligand receptor gene and the drug resistant gene into a cytokine dependent cell line (non-cancer cell), although the establishment of the oncogene-expressing cell is not focused.
(3) Screening for Oncogene Targeting Drug
An example of a method for screening an oncogene targeting drug using a cell is a method of using a cancer cell line naturally expressing an oncogene (hereinafter, conventional screening method 1).
Another example of the method for screening the oncogene targeting drug using the cell is a method of using a cell in which an oncogene has been introduced (hereinafter, conventional screening method 2). For example, Non-patent Literature 1 discloses that the EML4-ALK gene was introduced into a murine IL-3 dependent cell line (non-cancer cell line, Ba/F3 cell line) and effects of a molecular targeting drug that targeted the EML4-ALK gene was verified.
Patent Document 1 discloses that the ligand or the ligand-like substance can be screened by using the aforementioned cell line derived from the cytokine dependent cell line (non-cancer cell line), although the screening for the oncogene targeting drug is not focused.